<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
          function isZhiShu(n)
          {
              var isZS =  true;
              for(var i=2;i<Math.sqrt(n);i++)
              {
                  if(n%i==0)
                  {
                      isZS =false;
                      return isZS;
                  }
              }

          } 
          console.log('9:'+isZhiShu(9));
          console.log('7:'+isZhiShu(7));
    </script>
</body>
</html>